JPS6093860A - High frequency oscillating circuit - Google Patents

Abstract

PURPOSE:To attain long service life of a battery by connecting two resonance circuits having a resonance frequency different slightly to one crystal oscillator in parallel and switching alternately them with an output of a digital logical circuit. CONSTITUTION:A microcomputer 2 is operated by a battery power supply 3, a signal S1 is outputted only at signal transmission and outputs either a signal S2 or S3 depending on the state of a sensor 1. A transistor Q1 is turned on when the signal S1 is at a low level and gives power to a high frequency oscillation circuit. Two capacitors are connected respectively in parallel with a common inductance of a crystal oscillator 4 via switching diodes D1, D2. When the signal S2 is at a low level, the switching diode D1 is turned on, the oscillation circuit is oscillated at a frequency f1 and when the signal S3 is at a low level, the switching diode D2 is turned on and a frequency f2 is oscillated.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a high-frequency wave oscillation circuit for FM-modulating and wirelessly transmitting a binary signal, and in particular, it relates to a high-frequency wave oscillation circuit for FM-modulating a binary signal and transmitting it wirelessly, and in particular, it relates to a high-frequency wave oscillation circuit for wirelessly transmitting a binary signal by FM modulating the signal, and in particular, it relates to a high-frequency wave oscillation circuit for wirelessly transmitting a binary signal by FM modulating the signal. It is applied to wirelessly transmit data to a central controller.

<Prior art> Conventional transmitters generally use variable capacitance diodes, but with these, the frequency deviation required for frequency modulation cannot be obtained, and the power supply is caused by batteries. There were drawbacks such as the frequency deviation position becoming unstable due to fluctuations.

<Disclosure of the Invention> The present invention was invented in order to eliminate the above-mentioned drawbacks, and is a method in which two resonant circuits with slightly different resonant frequencies are connected in parallel to one crystal oscillator. It is characterized in that it is configured to be alternately switched by the output of a digital logic circuit such as a microcomputer.

<Example> FIG. 181 shows a circuit diagram of an embodiment of the present invention.

The sensor 1 is, for example, a fire sensor, a gas sensor, a bath temperature sensor, a window glass breakage sensor, an open door sensor, etc., and can be equivalently represented by an open/close switch S. The microcomputer 2 is operated by a battery power source 3, outputs a signal S1 only during signal transmission, and outputs either a signal S2 or S3 depending on the state of the sensor 1. This signal S2 or S3 includes, in addition to the status signal of the sensor 1, a house code specific to the house, a code for setting a room or bathroom, a door, etc. Figure 2 shows these output signals Sl
, S2. An example of a time chart of S3 is shown.

Transistor Q1 is for ON/OFF control of the power supply from the battery 3 to the high frequency oscillation circuit, and when the signal S1 is at the Lo level, Ql is turned on, and the voltage divided by the power supply Vcc and resistors R4 and R5 is , a divided voltage by resistors R6 and R7 is supplied to each part of the circuit.

Circuit 3 is a constant current circuit and outputs a constant current output signal S2' or S3' according to the input signal S2 or S3. When signal S2 goes to Lo level, transistor Q4 turns on.
The switching diode D1 is controlled by the current defined by the Zener diode ZD2 and the resistor R]2.
turns on.

Similarly, when the signal S3 becomes LO level, the transistor Q5 is turned on, and the switching diode D2 is turned on.
turns on.

The crystal oscillator 4 has a common inductance L3 of 2
Capacitors C1 and C2 are connected in parallel, one end of capacitor CI is grounded via the switching diode DI mentioned above, and one end of capacitor C2 is grounded via switching diode D2. This oscillation circuit has a first frequency f when the diode DI is turned on.
l, e.g. 50,0OOK Hz, and when the diode D2 is turned on, the second frequency 12, e.g. 5
Capacitors C1 and C2 to oscillate at 0,001KHz
Constants such as Note that the inductance Ll
.

L2 is for reducing external influences on the crystal oscillation circuit. Capacitors C3 and C4 form a feedback circuit, and the capacitance is selected to be larger than the input capacitance and output capacitance of transistor Q2 to reduce the influence of the transistor.

Transistor Q2 serves both as amplification and frequency multiplication, and is multiplied by three in this stage. Inductance L5 and capacitor C5 are a tuning circuit for triple multiplication, and inductances 1 and 9 and capacitor c8 are filters for reducing frequency components other than triple multiplication.

Transistor Q3 serves both as amplification and frequency multiplication, and is further doubled in this stage to obtain a high frequency six times that of the original oscillation. Inductance L6 and capacitor CI2 are a tuning circuit for 6 multiplication, inductance 1.7 and capacitor C1l are a circuit for reducing unnecessary radiation, inductance L8 and capacitor C10 are antenna 5.
This is a resonant circuit that efficiently radiates only the multiplied frequency. The antenna 5 has a signal S2 of Lo, but a signal s3 of
According to whether is I or 0, f I= 6X50,000=300,000 K H
z or f 2 = 6x50,001 = 300,006
Predetermined code information is emitted while being alternately switched between two KHz frequencies as illustrated in the time chart of FIG. A central controller (not shown) receives and demodulates this FM modulation frequency to obtain a serial signal of the time chart illustrated in FIG.

FIG. 3 shows another embodiment of the oscillation circuit of the present invention.

This circuit differs from the one in Figure 1 by omitting the output signal S3 of the computer 2 and its related circuits, by connecting a capacitor C2' instead of the capacitor C2 that determines the oscillation frequency, and by connecting one end of the capacitor C2'. It was grounded all the time.

According to this embodiment, as soon as the signal S1 goes LO and power is supplied to the oscillation circuit, L3. Oscillation is caused at a first frequency determined by C2', and only when the computer output signal S2 becomes LO, the capacitor C1 is connected in parallel with the capacitor C2' by conduction of the switching diode D1 to obtain the necessary frequency deviation.

<Effects of the Invention> According to the present invention, the transistor Q1 is turned on for a predetermined period of time by a computer and power is supplied to the high frequency oscillation circuit, so that the life of the battery can be extended. In addition, since the crystal oscillation circuit is energized by the constant current circuit, oscillation is maintained stably even if the battery voltage drops a little, and the frequency deviation is obtained by changing the capacitance of the oscillation circuit using a computer, making it extremely easy to use. ``ζ A stable FM modulation signal can be obtained.

[Brief explanation of the drawing]

1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is an explanatory diagram of the operation of FIG. 1, and FIG. 3 is a circuit diagram showing another embodiment of the crystal oscillation circuit of FIG. 1. 1-Sensor 2-Microcomputer 3 Constant current circuit 4-Crystal oscillator C1, C2, C2'-Capacitor r)l, Dl---Switching diode Patent applicant Sharp Corporation agent Patent attorney Arata Nishida Tokukai Sho G O-938G O(4)

Claims (2)

[Claims] (1) A crystal oscillation circuit that includes two types of resonant circuits and selectively outputs one of two different predetermined frequencies, and the output level changes over time depending on the code information to be transmitted.2
The value signal output means and the binary signal output means allow the above-mentioned 2
A high frequency oscillation circuit having a switching means for switching between different types of resonant circuits. (2) Two capacitors forming two types of resonant circuits,
Claims include a switching diode connected in series with at least one of the capacitors, and a constant current circuit for controlling on/off of the switching diode.$
The high frequency oscillation circuit described in item 1.